Bodhi (Sanskrit: बोधि; and Pali) in Buddhism is the understanding possessed by a Buddha regarding the true nature of things. It is traditionally translated into English with the word enlightenment and literally means awakened. (The verbal root "budh" means to awaken.) Bodhi is knowledge of the causal mechanism by which beings incarnate into material form and experience suffering. Although its most common usage is in the context of Buddhism, bodhi is also present as a concept in other Indian philosophies and traditions.

The soteriological goal of Indian religions is liberation or moksha (also called mukti). Liberation is simultaneously freedom from suffering and the endless round of existences. Within the Sramanic traditions one who has attained liberation is called an arhat (Sanskrit; Pali: arahant), an honorific term meaning "worthy" acknowledging the skill and effort required to overcome the obstacles to the goal of nirvana.

According to the Buddha[citation needed] the path to liberation is one of progressively coming out of delusion (Pali: Moha). This path is therefore regarded as a path of awakening. Progressing along the path towards Nirvana one gains insight into the true nature of things. A Buddha is one who has attained liberation and an understanding of the causal mechanism by means of which sentient beings come into existence. This mechanism is called pratitya samutpada or dependent origination. The knowledge or understanding of this is called bodhi.

Awakening is also described as synonymous with Nirvana, the extinction of the passions whereby suffering is ended and no more rebirths take place.[8] The insight arises that this liberation is certain:

Knowledge arose in me, and insight: my freedom is certain, this is my last birth, now there is no rebirth.[9]

So awakening is insight into karma and rebirth, insight into the Four Noble Truths, the extinction of the passions whereby Nirvana is reached, and the certainty that liberation has been reached.[9]

Arhat (Pali: arahant), those who reach Nirvana by following the teachings of the Buddha.[14] Sometimes the term Śrāvakabuddha (Pali: sāvakabuddha) is used to designate this kind of awakened person[citation needed];

Pratyekabuddhas (Pali: paccekabuddha), those who reach Nirvana through self-realisation, without the aid of spiritual guides and teachers, but don't teach the Dharma;[14]

Samyaksambuddha (Pali: samma sambuddha), often simply referred to as Buddha, one who has reached Nirvana by his own efforts and wisdom and teach it skillfully to others.[14]

In early Buddhism, bodhi carried a meaning synonymous to nirvana, using only some different metaphors to describe the insight, which implied the extinction of lobha (greed), dosa (hate) and moha (delusion). In Theravada Buddhism, bodhi and nirvana carry the same meaning, that of being freed from greed, hate and delusion.

Bodhi is the final goal of a Bodhisattva's career [...] Bodhi is pure universal and immediate knowledge, which extends over all time, all universes, all beings and elements, conditioned and unconditioned. It is absolute and identical with Reality and thus it is Tathata. Bodhi is immaculate and non-conceptual, and it, being not an outer object, cannot be understood by discursive thought. It has neither beginning, nor middle nor end and it is indivisible. It is non-dual (advayam) [...] The only possible way to comprehend it is through samadhi by the yogin.[17]

According to these doctrines bodhi is always there within one's mind, but requires the defilements to be removed. This vision is expounded in texts such as the Shurangama Sutra and the Uttaratantra.

In Shingon Buddhism, the state of Bodhi is also seen as naturally inherent in the mind. It is the mind's natural and pure state, where no distinction is being made between a perceiving subject and perceived objects. This is also the understanding of Bodhi found in Yogacara Buddhism and the mind's natural and pure state as in Dzogchen.

To achieve this vision of non-duality, it is necessary to recognise one's own mind:

... it means that you are to know the inherent natural state of the mind by eliminating the split into a perceiving subject and perceived objects which normally occurs in the world and is wrongly thought to be real. This also corresponds to the Yogacara definition ... that emptiness (sunyata) is the absence of this imaginary split[18]

During the development of Mahayana Buddhism the various strands of thought on Bodhi were continuously being elaborated. Attempts were made to harmonize the various terms. The Buddhist commentator Buddhaguhya treats various terms as synonyms:

For example, he defines emptiness (sunyata) as suchness (tathata) and says that suchness is the intrinsic nature (svabhava) of the mind which is Enlightenment (bodhi-citta). Moreover, he frequently uses the terms suchness (tathata) and Suchness-Awareness (tathata-jnana) interchangeably. But since Awareness (jnana) is non-dual, Suchness-Awareness is not so much the Awareness of Suchness, but the Awareness which is Suchness. In other words, the term Suchness-Awareness is functionally equivalent to Enlightenment. Finally, it must not be forgotten that this Suchness-Awareness or Perfect Enlightenment is Mahavairocana [the Primal Buddha, uncreated and forever existent]. In other words, the mind in its intrinsic nature is Mahavairocana, whom one "becomes" (or vice versa) when one is perfectly enlightened.[18]

Kenneth R. White (editor) (2005), The Role of Bodhicitta in Buddhist Enlightenment including a Translation into English of the Bodhicitta-Sastra, Benkenmitsu-nikyoron, and Sammaya-kaijo. New York : The Edwin Mellen Press